As a conventional high-speed optical delay generating method in optical coherence tomography, a method has been known, in which the light-path for reference light extends through a half mirror, a first mirror, a second mirror, and the half mirror, and the boundary between the first mirror and the second mirror is set to be the reflection center.
FIG. 1 schematically shows the configuration of a conventional optical coherence tomography device. This figure shows a low-coherence light source (e.g., an SLD (super luminescent diode) light source) 101, a half mirror (two-splitting half mirror) 102, a rotating member 103, a first mirror 104A, a second mirror 104B, mirrors 105 and 106, an object A to be examined, and a light detector 107.